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IQ.ts

Complete Image Quantization Library in TypeScript (MIT License)

demo github npm version API Documentation NPM License

quantization

Table of Contents

Introduction

Image Color Number Reduction with alpha support using RgbQuant/NeuQuant/Xiaolin Wu's algorithms and Euclidean/Manhattan/CIEDE2000 color distance formulas in TypeScript

Capability

  1. Platforms supported

    • browser (Chrome 7.0+, FireFox 4.0+, IE 10+, Opera 11.6+, Safari 5.1+)
    • node.js (Node.js 0.9.0+)

  2. Builds

    • dist/browser-iq.js - JavaScript build for browser (global var IQ)
    • dist/node-iq.js - JavaScript build for Node.js (module.exports = IQ)
    • src/iq.ts - TypeScript module (use /// <reference path="path-to-library/src/iq.ts" />)

  3. Import

    • HTMLImageElement
    • HTMLCanvasElement
    • NodeCanvas
    • ImageData
    • Array
    • CanvasPixelArray
    • Uint8Array
    • Uint32Array

  4. Color Distance

    • Euclidean - originally used in Xiaolin Wu's Quantizer WuQuant
    • EuclideanRgbQuantWOAlpha (sRGB coefficients/without alpha support) - originally used in RgbQuant
    • EuclideanRgbQuantWithAlpha (sRGB coefficients)
    • Manhattan - originally used in NeuQuant
    • ManhattanSRGB (sRGB coefficients)
    • CIEDE2000_Original - full CIEDE2000 implementation (very very very slow)
    • CIEDE2000 - part of formula was stripped as it meaningless for JavaScript floating-point precision/RGB 8bit per channel converted to Lab (very very slow)
    • CIE94 - full CIE94 implementation
    • CMETRIC
    • PNGQUANT - used in pngQuant tool

  5. Palette Quantizers

    • NeuQuant (original code ported, integer calculations)
    • RgbQuant
    • WuQuant
    • NeuQuantFloat (floating-point calculations)

  6. Image Quantizers

    • NearestColor
    • ErrorDiffusionArray - two modes of error propagation are supported: xnview and gimp
      1. FloydSteinberg
      2. FalseFloydSteinberg
      3. Stucki
      4. Atkinson
      5. Jarvis
      6. Burkes
      7. Sierra
      8. TwoSierra
      9. SierraLite
    • ErrorDiffusionRiemersma - Hilbert space-filling curve is used

  7. Output

    • Uint32Array
    • Uint8Array

Include IQ Library into your project

TypeScript + Node.js/Browser project
/// <reference path='<path-to-iq>/src/iq.ts' />
JavaScript + Node.js project
var iq = require("<path-to-iq>/dist/node-iq.js");
JavaScript + Browser project
<script src="<path-to-iq>/dist/browser-iq.js" type="text/javascript" charset="utf-8"></script>

Usage

Load Image (simple example)
var img = document.createElement("img");
img.onload = function() {
	// image is loaded, here should be all code utilizing image
	...
}
img.src = "http://pixabay.com/static/uploads/photo/2012/04/11/11/32/letter-a-27580_640.png"
Generate Palette
// desired colors number
var targetColors = 256;
   
// create pointContainer and fill it with image
var pointContainer = IQ.Utils.PointContainer.fromHTMLImageElement(img);

// create chosen distance calculator (see classes implementing `IQ.Distance.IDistanceCalculator`)
var distanceCalculator = new IQ.Distance.Euclidean();

// create chosen palette quantizer (see classes implementing `IQ.Palette.IPaletteQuantizer`) 
var paletteQuantizer = new IQ.Palette.RgbQuant(distanceCalculator, targetColors);
		
// feed out pointContainer filled with image to paletteQuantizer
paletteQuantizer.sample(pointContainer);

... (you may sample more than one image to create mutual palette) 

// take generated palette
var palette = paletteQuantizer.quantize();
Apply Palette to Image (Image Dithering)
// create image quantizer (see classes implementing `IQ.Image.IImageDitherer`)
var imageDitherer = new IQ.Image.NearestColor(distanceCalculator);

// apply palette to image
var resultPointContainer = imageQuantizer.quantize(pointContainer, palette);

You may work with resultPointContainer directly or you may convert it to Uint8Array/Uint32Array

var uint8array = resultPointContainer.toUint8Array();

TODO

  1. notification about progress
  2. riemersma dithering
  3. ordered dithering

Changelog

0.1.4 (2015-06-24)
+ Refactoring 
+ Riemersma dithering added (Hilbert Curve)
+ Readme.md updated
+ build.cmd updated
0.1.3 (2015-06-16)
+ NeuQuant is fixed (again) according to original Anthony Dekker source code (all values should be integer)
+ Error Diffusion Dithering is now calculates error like XNVIEW
+ Refactoring
0.1.2 (2015-06-16)
+ Documentation generation fixed
+ File name case problem fixed
0.1.1 (2015-06-16)
+ Auto-generated documentation added
+ Refactoring
0.1.0 (2015-06-16)
+ Code cleanup, removed unnecessary files
0.0.5 (2015-06-16)
+ PNGQUANT color distance added, need to check its quality
+ CIEDE2000 and CIE94 fixed for use in NeuQuant
+ NeuQuant is fixed according to original Anthony Dekker source code (all values should be integer) 
+ Code refactoring and cleanup
* We have some slowdown because of red/green/blue/alpha normalization according to white point per each calculateRaw/calculateNormalized call
0.0.4 (2015-06-15)
+ CIEDE2000 color distance equation optimized (original CIEDE2000 equation is available as class `CIEDE2000_Original`)
0.0.3b (2015-06-11)
+ CMETRIC color distance fixed
0.0.3a (2015-06-11)
+ Cleanup
+ Draft of CMETRIC color distance added
0.0.2 (2015-06-10)
+ rgb2xyz & xyz2lab fixed. CIEDE2000 works much better now.
+ CIE94 distance formula added. More investigation is needed.
0.0.1
+ Initial

Credits

Thanks to Leon Sorokin for information share and his original RgbQuant!

References

Be sure to fix rgb2xyz/xyz2lab. Issue is with strange part of code: r = r > 0.04045 ? .... Check http://en.wikipedia.org/wiki/Lab_color_space

License

MIT